Index targets hit, not sources of damage. You’ll have to search through the list of targets hit to avoid duplicates (instead refresh the damage). Post your code.
Not entirely sure what you mean by index targets. To be honest i'm a total noob at this. My code is probably awful, I was just testing out different thing to see what worked how.
Nature Arrow Effect
Events
Game - DamageEvent becomes Equal to 1.00
Conditions
Or - Any (Conditions) are true
Conditions
((Attacked unit) has buff Nature Arrow Poison (Non-stacking)) Equal to True
((Attacked unit) has buff Nature Arrow Poison (Stacking)) Equal to True
Actions
Countdown Timer - Start NatureArrow_Timer as a One-shot timer that will expire in 3.00 seconds
Set DamageEventSource = (Damage source)
Set DamageEventTarget = (Attacked unit)
Set ArrayInteger = (ArrayInteger + 1)
Unit - Set the custom value of (Attacked unit) to ArrayInteger
Set ArrayTarget[(Custom value of DamageEventTarget)] = (Attacked unit)
Set Damagething = (0.67 x (Real((Agility of DamageEventSource (Include bonuses)))))
Unit - Set mana of DamageEventSource to ((Mana of DamageEventSource) - 3.00)
For each (Integer A) from 1 to ArrayInteger, do (Actions)
Loop - Actions
Trigger - Turn on Nature Arrow Loop <gen>
Following that the loop is just a loop that deals damage to the target every second